Method of synthesizing gasoline and the like



Dec. 26, 1950 H. v. ATWELL METHOD oF 'SYNTHESIZING GAsoLINE ANDTHE LIKE ifi-led July 27, 194e INVENTOR.

Patented Dec. 26, 1950 METHDD F SYNTHESIZING GASOLINE AND THE LIKE Harold V. Atwell, Beacon, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application July 27, 1946, lSerial No. `686,655

(Cl. Zim-449.6)

10 Claims.

This invention relates to the catalytic conversion of synthesis gas comprising carbon monoxide and hydrogen into hydrocarbons, oxygen-containing compounds and the like and more particularly to an improved method for effecting such conversion employing direct contact evaporative cooling.

The invention contemplates contacting synthesis gas with a catalyst in a. conversion zone wherein the temperature is maintained within the desired range by direct contact evaporative cooling. An effluent is discharged from the conversion zone and is split into two streams. One stream is di'- verted to a product recovery system. The other stream from which the recycle streams are derived is further sub-divided into two portions. One portion is contacted with a cooling liquid,

which advantageously is a selective absorbent for.

Water or carbon dioxide, to effect at least partial condensation and removal of the normallyk liquid components present therein as Well as removal of carbon dioxide when desired. The'cooled uncondensed gas from this treatment is combined with the remaining po-rtion so as to effect condensation of higher boiling constituents thereof in the form of a fog uniformly dispersed throughout a body of uncondensed gas. A stream comprising this resulting mixture of gas and highly atomized liquid is recycled to the conversion zone where the atomized liquid components serve as an evaporative coolant.

This invention prevents association of coolant with catalyst particles which interferes with the essential functions of reactant adsorption and product desorption from the catalyst' active centers. It is particularly applicable with a fluidized solid catalyst operation wherein muddying or slurrying of the catalyst is to be avoided. The pre-atomization of the evaporative coolant eliminates the presence of large globules of liquid in the reaction zone which would result in mudding and agglomeration of a powdered or nely divided catalyst.

As a matter of fact, such an improvement is Wrought in evaporative cooling technique by this invention that its use results in more uniform fluidization of catalyst in fluid operations. The volume decrease accompanying the conversion of hydrogen and carbon monoxide into hydrocarbons is oiiset by the vaporization of pre-atomized coolant.

The aforesaid liquid Which is used to cool one4 of the recycle streams is advantageously an absorbent ior Water.

Ethylene glycol is an exam- 'V ple of a liquid which may advantageously be usedv ethylene glycol and glycerine may also be used as liquid coolants.

Reduction of the water concentration in the recycle stream by the use of a selective absorbent for water such as ethylene glycol minimizes carbon dioxide formation in the conversion. Reduction of carbon dioxide formation in the conversion allows greater production of valuable hydrocarbon per unit of carbon introduced into the reactor.

As previously indicated the liquid which is used to cool the recycle stream may be a selective absorbent for carbon dioxide. The use of a carbon dioxide absorbent such as monoethanolamine may replace the use of a Water absorbent for the cooling of the recycle stream. Alternatively, the recycle stream may be subjected to countercurrent contact with an absorbent for carbon dioxide in addition to the contact with a selective absorbent for water.

The remo-val of carbon dioxide from the re' cycle stream provides a hydrogen-rich recycleA gas which is` advantageous under reaction conditions for the suppression of coke and wax formation.

A recycle ratio expressed as volume of recycle gas per volume of fresh feed may be employed within the limits oi about 0.5:1 to 4:1. Normally a 1:1 or 2:1 ratio is employed.

Reference will now be made to the accompanying drawing in order to present a fuller exposition of the method of the invention. The drawing presents the method of the invention diagrammatically since it is thought that the invention may be completely understood Without reference to a more detailed sketch.

Synthesis gas comprising carbon monoxide is obtained from a source not shown through a conduit l. Synthesis gas may be prepared by a number of well-known methods such as the Water.

gas reaction or the oxidation of methane with a limited quantity of oxygen. The synthesis gas may be obtained at the desired temperature and pressure levels through the use of conventional f heaters and compressors which are not shown.

Recycle gas, obtained from sources which will be described in detail later, combines with fresh synthesis gas in the conduit l. A total reactor feed comprising fresh synthesis gas, recycle gas and evaporative coolant dispersed in the form of a fog is introduced into the reactor 4 through the conduit l. Provision is made for multiple injection of the total reactor feeda manifold.

pipe 5 connects with the conduit l and a desired portion of total reactor feed may be diverted through the manifold pipe 5 and introduced into the reactor 4 at successive points along the vertical dimensions of the reactor 4 through pipes 6, l, 8 and 9. Multiple injection of reactor feed containing atomized coolant insures uniform removal of heat of reaction throughout the reactor Il.

In the reactor 4, there is maintained a uidized mass c-f solid catalyst particles. The constitution of the catalyst and the nat-ure of the desired products determines the temperature at which the conversion takes place in the reactor'li. YIn general, temperatures between about 250 F. V`and '700 E'. are employed for the-hydrogenation of carbon monoxide.

A space velocity which is dened as the volume' of gas per volume of fluidized catalystper hour is employed which lies between about `500 and 3090. Ordinarily a space velocity of 1060 or 1500 is used to maintain the catalyst in dense phase fiuidization without substantial entrainmentl of catalyst particles in the gaseous eliluent from the reactor.

Synthesis gas is converted vinto desired cornpounds by contact .with a suitable catalyst in the reactor Iron, cobalt and nickel are usually the active metals from which supported or unsupported catalysts are prepared. vPromoters such as the oxides of magnesium, thorium, vanadium, manganese, etc., are employed to improve the efficiency of the catalyst. .An example of a catalyst which serves well for a conversion performed in accordance with the iiuid technique isan unsupported iron catalyst whoseconstitution may approximately be represented as follows: 94 to 97 per cent iron, 2 to 5 per cent aluminaand to 2 per centalkali metal oxide such aspotassia.

The heat liberated during Ythe vcatalytic conversion is mainly absorbed as the llatent heat of vaporization of evaporative coolant which is introduced into the reactors in an atomized state. Further `temperature control Vis provided by the absorption of heat of reaction as the sensible heat of three components, namely recycle gas, fresh synthesis lgas and atomized liquid coolant.

Ahgh percentage conversion of synthesisgas perepass is obtained making possible the attainment of high space-time yields .which are essential Lfor successful commercial operation. 9.0 per per cent and better conversions of carbon `monoxide are obtainedvperrpass.

An effluent stream leaves the reactor 4 through a :pipe I2. This effluent comprises products of conversion, a small percentage of unreacted synthesis gas and vaporized .liquid coolant. A portion of the eluent is diverted from the pipe l2 through a pipe I 3 through which it is ledto a product recovery system which contains the .conventional units of fractionation, stabilization, etc. `In the product recovery system, the normally gaseous components of the eifluent are separated from the normally liquid constituents which are then further separated intorgasollne, gas oil, fuel oil, etc.

Another portion of the eiuent from which the recyclestreamsare to be obtained, is diverted into a pipe Id through which itis introduced into a vessel l which serves as a combination scrubber and cooler.

In the Vtwo-function vessel l5, this portion of the effluent is subjected te counter-current contact with a cooling liquid which is advantageously an .absorbent for water. The liquid coolant advantageously is introduced into the vessel at about 100 to ZGO" F. in the form of a sprayV f, ufl

tial solution in the selective absorbent which is employed as a liquid coolant. Further cooling may be effected in the vessel l5- if desired by inserting therein a coil through which a cooling ;medium is passed; this coil is not shown in the drawing.

Liquid-:coolant-and condensed components of the eiliuent leave the vessel I5 through a pipe i?. .Further `treatmentof this liquid phase will be described in detaill later.

A gas stream comprising mainly the normally Agaseous products or" conversion, carbon dioxide,

unreacted carbon monoxide and hydrogen issues from the vessel l5 through a pipe i8 at a temperature 20D-400 F. below the temperature at which thestream of ,products is introducedinto the vessel i5. This gas stream may be treated Yto remove carbon dioxide therefrom in a separate vessel or it may be used directly to effect condensation of the other recycle stream in the form of a fog.

If the gas stream issuingfrom the vessel I5 is to be used directly to effect condensation of the higher boiling components of the recycle gas stream, it is diverted Vfrom the pipe i8 along a pipe i9 which leads .to a pump 20. From the pump 2li the cool gas stream proceeds along the pipe 2l until it combines with the other portion of the elliuent from the reactor l! which is used as a recycle stream.

As was mentioned previously, the ellluent from the reactor f from which the recycle streams are derived is divided into two portions, Treatment of one of these portions has just been described. The other portionis diverted from the Vpipe l2 toa pipe 22 through which it is introduced into a separator '23 wherein entrained liquid and waxy components are separated from the gas stream. The separated liquid and waxy components ilow 'from the separator 23 to a pipe 24 into the pipe I3 which leads vto the product recovery system which has been alluded to previously.

A gas stream leaves the separator 23 through a pipe V25 at a temperature which is substantially equivalent to that maintained in the reactor Il. This gas stream proceeds through a pump 2G and a pipe 21 to the conduit l through which fresh synthesis gas is introduced into the reactor d. The other recycle gas stream which is at a temperature substantially below conversion temperature also combines with the fresh synthesis gas in the conduit I to give a reactor feed comprising fresh synthesis gas and recycle gas,

The merging of the hot recycle gas stream with cool fresh synthesis gas and with the cool recycle gas stream results in the condensation of the higher boiling components of the hot recycle stream in a finely dispersed form. These atomized constituents of the conversion product are substantially vaporizable under the conversion conditions and serve excellently as a liquid evaporative coolant in the reactor 4.

Thus the total reactor feed introduced into the reactor 4 comprises fresh synthesis gas, recycle gas Yand entrained atomized evaporative coolant.

Returning to the liquid phase comprising liquid coolant such as ethylene glycol and condensed components of the effluent which leaves the vessel i5 through the pipe il, it is introduced into a separator 3&3. In the separator 3U, a hydrocarbon phase is separated from the heavier liquid absorbent and is led to a product recovery system through a pipe 3|. This product recovery system is similar to that which has been alluded to in connection with the treatment of the portion of the emuent from the reactor 4 which is introduced into a product recovery system through the pipe |3.

The liquid coolant containing water and a major portion of the alcohols produced in the conversion leaves the separator 30 through a pipe 32 and is introduced into a fractionating column 34. In the fractionating column 34, alcoholwater azeotropes are distilled from the liquid absorbent and leaves the column 34 through a pipe 35. Water is distilled and removed from the column 34 through a pipe 36.

The high-boiling absorbent leaves the column 34 through a pipe 31 through which it is introduced into an exchanger 38 in which it is brought to the desired temperature. The coolant at the desired temperature leaves the exchanger 38 through a pipe 39 through which it is introduced into the vessel l5. The nozzle I6 is used to effect the introduction of the liquid absorbent in a finely divided form.

As indicated previously the gas stream issuing from the vessel |5 may be subjected to treatment with a selective absorbent for carbon dioxide. If this procedure is followed the gas stream is diverted from the pipe I8 through a pipe 40 into a tower 4|. In the tower 4| the gas stream is subject to countercurrent contact with a cool liquid such as monoethanolamine which is a selective absorbent for carbon dioxide. By this treatment carbon dioxide is removed from the gas stream and a hydrogen-rich gas stream issues from the tower 4| through a pipe 42. This hydrogen-rich gas stream is then introduced into the pipe I9 through which it is introduced in succession through the pump 20 and the pipe 2| into the conduit l. This cool hydrogen-rich gas stream serves the same function in the conduit as has been described previously for the recycle stream which was only subjected to cooling and scrub- .r

bing with an absorbent for water; namely, it aids in the condensation of the higher boiling components of the hot recycle stream in the form of a fog.

The liquid absorbent containing absorbed carbon dioxide leaves the tower 4| through a pipe 43 which leads to a stripper 44. In the stripper 44 carbon dioxide is driven off from the liquid absorbent and a gaseous stream of carbon dioxide is discharged from the stripper 44 through a if pipe 45.

Stripped absorbent leaves the stripper 44 through a pipe 46, is cooled in the exchanger 41 and is then introduced into the tower 4I through a pipe 48 and a spray nozzle 49.

By way of example, fresh synthesis gas containing carbon monoxide and hydrogen in the molecular ratio of about 1:2 is passed into a reactor 4 containing an iron catalyst of the type previously described. The iron catalyst is maintained in a uidized state in the reactor 4.

A recycle gas containing atomized condensed constituents of the products is combined with fresh synthesis gas in the conduit in the proportion of about two volumes of recycle gas to one volume of fresh synthesis gas.

The quantity of condensed atomized compo-I nents in the recycle gas is regulated so that 0.2 barrel of liquid is introduced into the reactor in every thousand cubic feet of mixed synthesis gas and recycle vapor.

The total reactor feed is charged to the reactor 4 at a rate of about 1,000 cubic feet (measured at standard conditions) per cubic feet oi iiuidized catalyst per hour. The temperature within the reactor is maintained at about 600 F. 'I'he temperature of the reactor feed as it is introduced into the reactor 4 is about 350 to 375 F.

The yield of C5 and heavier hydrocarbons separated from the eiuent of a fluid operation conducted in this manner amounts to approximately one gallon of hydrocarbons per thousand cubic feet of fresh synthesis gas.

In the description of the invention, condensation in the form of a fog of the higher -boiling components of the hot recycle gas has been effected by addition thereto of a cool gas stream consisting of the lower boiling products of conversion. It is contemplated that the aforesaid fog formation may be effected by injecting a cool gas or refrigerant, such as liquid pentane, through a pipe 50 into the hot recycle stream in an amount sufficient to reduce the temperature of the stream below the dew point of a portion of the higher boiling constituents of the stream.

It is contemplated that the invention may be adapted to conversions in which a plurality of stages connected in series is used. In this instance, a portion of the effluent from each stage may be Withdrawn, contacted with a cooled selective absorbent for water vapor and then the cooledAnon-condensed components of the withdrawn eiiluent combined with the reactor feed to the next stage. The introduction of cool gas into the effluent from one stage as it passes to the next succeeding stage causes condensation of the higher boiling components thereof in a finely dispersed state. The condensed higher boiling components then serve as an evaporative coolant for the succeeding stage. This operation is repeated between each stage. thereby providing for atomized liquid coolant for each stage.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and. therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. In the catalytic conversion of synthesis gas comprising carbon monoxide and hydrogen into hydrocarbons, oxygen-containing compounds and the like wherein heat of reaction is removed by evaporation of a finely dispersed coolant in direct contact with the catalyst, the method which comprises contacting synthesis gas in a conversion zone with a catalyst under suitable conditions to effect conversion into desired compounds, removing an eiiiuent comprising normally gaseous and normally liquid products of conversion from said conversion zone, diverting a portion of said eiiluent to a product recovery system, dividing another portion of said effluent into two streams, cooling one of said streams to remove normally liquid constituents, combining cooled uncondensed gas from said cooling treatment with hot gases containing higher boiling components of the other of said streams so as to effect condensation of higher boiling components of said other stream in the form of a fog, recycling said combined stream retaining fog therein to said conversion zone to supply said coolant, and retaining a recycle ratio of recycle gas to fresh feed between 0.5 to l and 4 to l. v

2. In the catalytic conversion of synthesis gas comprising carbon monoxide hydrogen into hydrocarbons, oxygen-containing compounds and the like wherein heat of reaction is removed by evaporation cf a finely dispersed coolant in direct Contact with the catalyst, the method which comprises contacting synthesis gas in a conversion zone with a catalyst under suitable condi= tions to effect conversion into desired compounds, removing' an effluent comprising normally gaseous and normally liquid products of conversion from said conversion zone, diverting a portion of said reilluent to a vproduct recovery system, vcooling another portion of said eiiluent by introduction therein of a vapori'zable liquid hydrocarbon so as to leffect condensationv of higher boiling com'- ponents of'said stream in the form of a fog, recycling said treated stream which retains said fog therein to said conversion zone to supply coolant, 'and retaining a recycle ratio "of recycle gas to fresh feed between 0.'5' to 1 and '4 to 1.

3. -In the catalytic conversion of synthesis gas comprising carbon monoxide 'and hydrogen into hydrocarbons, oxygen-containing compounds'and the' like wherein heatoi reaction is removed by evaporation of 'a finely dispersed coolant in direct contact with the catalyst, the' method which comprise's'contacting synthesis gas' in a conversion Zone with va catalyst under' suitable conditions to effect conversion into desired compounds, removing an eiiluent comprising normally gaseous and normally liquid products of conversion from said conversion zone, diverting a portion of said effluent to a productrecove'ry system, cooling another portion of said eiliuent by the injection of liquid pentane therein so as to eiTect condensation of higher boiling comitgonentsY of said stream in the form of a fog and recycling said cooled stream which retains said fog therein to said conversion Zone.

4. In the catalytic conversion of synthesis gas comprising carbon monoxide and hydrogen into hydrocarbons, oxygen-containing eompoundsand the like wherein heat of reaction is removed by evaporation of a finely dispersed coolant in direct contact with the catalyst, the method which comn prises contacting synthesis gas in a Vconversion zone with a catalyst under suitable conditions to eect conversion into desired compounds, removing an efiiuent comprising normally gaseous and normally liquid products of conversion from said conversion Zone, diverting a portion of said effluent to a product recovery system, dividing another portion of said effluent into two recycle streams, passing one of said recycle streams to a cooling zone, effecting condensation therein of normally liquid constituents by direct contact with a liquid absorbent for water, removing resulting condensate from said condensation, combining uncondensed gas from said treatment with hot gases containing higher boiling components of the other of said recycle streams so as to eie'ct condensation of higher boiling components of said other stream in the form of a fog, recycling said combined stream which retains said fog therein to said conversion zone to supply sa-'d coolant, and retaining a recycle ratio of recycle gas to fresh feed between 0.5 to 1 and 4 to 1.

5. The method accordingv to claim 4 in which the cooled liquid absorbent is a glycol.

6. In the catalytic conversion of synthesis gas comprising carbon monoxide and hydrogen into hydrocarbons, oxygen-containing compounds and the like wherein heat of reaction is removed by evaporation of a nely dispersed coolant in direct contact' with the catalyst, the method which comprises contacting synthesis gas in a conversion zone with a catalyst under suitable condi'- tions to eiect conversion into desired compounds, removing anV effluent comprising normally gas- 'ecus' and normally liquid products' of conversion from said conversion zone, diverting a portion of said effluent to a product recovery system, dividing another portion of said eiiluent into two recycle streams, passing one of said streams to a cooling zone, effecting condensation therein of normally liquid constituents by direct contact with a liquid absorbent for carbon dioxide, removing resulting condensate from said condensation, separating at about conversion temperature liquid and waxy components from the other of said recycle streams, combining CO2-free gas; with said other recycle streams so as to effect condensation of higher boiling components of said other stream in the 'form of a fog, recycling said combined stream which retains said fog therein to said conversion 'zione to supply said coolant, and retaining a recycle rat-fo of recycle gas to fresh feed between 0.5 to 1 and 4 to 1.

7. The method according to claim 6 in which the cooled liquid absorbent is an allr'ylol-amine.

8. In the catalytic conversion of synthesis gas comprising carbon vmonoxide and hydrogen into hydrocarbons, oxygen-containing compounds and the like wherein heat of reaction is removed by evaporation of a nely dispersed coolant in direct Contact with the catalyst, the method which comprises contacting synthesis gas in a conversion Zone with a catalyst under suitable conditions to eiect conversion into desired compounds, removing an eluent comprising normally gaseous and normally liquid productsl of conversion from said conversion Zone, diverting a portion of said eiliuent into two recycle streams, passing one of said streams tov a cooling zone, effecting condensation therein of normally liquid constituents by direct contact with a cool liquid absorV- ent forl water, removing resulting condensate and water, contacting the eiu'ent from said condensation with an absorbent for carbon dioxide, separating at about conversion temperature liq`- uid and waxy components from the other of said streams, combining cool' Hgoand co2-free gas with said other recycle stream so as to eifect condensation of higher boiling components of said other stream in the form of a fog, recycling said combined stream which retains said fog therein to said conversion Zone to supply said coolant, and retaining a recycle ratio of recycle gas to fresh feed between 0.5 to 1 and 4 to 1.

9. The method according to claim 8 in which the cool liquid absorbent for water is a glycol.

10. The method according to claim 8 in which the cool liquid absorbent for carbon dioxide is an alkylol-amine.

HAROLD V. ATWELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,177,068 HutchinsOI Oct.` 24, 1939 2,243,869 Keith, Jr. et al June 3, 1941 2,279,052 Michael et al. v Apr. 7, 1942 2,406,851 Redcay Sept. 3, 1946 2,411,760 Sensel v Nov. 26, 1945 2,436,957 Eastman Mar. 2, 1943 FOREIGN PATENTS Number Country Date 739,569 Germany Oct. 4, 1943 

1. IN THE CATALYTIC CONVERSION OF SYNTHESIS GAS COMPRISING CARBON MONOXIDE AND HYDROGEN INTO HYDROCARBONS, OXYGEN-CONTAINING COMPOUNDS AND THE LIKE WHEREIN HEAT OF REACTION IS REMOVED BY EVAPORATION OF A FINELY DISPERSED COOLANT IN DIRECT CONTACT WITH THE CATALYST, THE METHOD WHICH COMPRISES CONTACTING SYNTHESIS GAS IN A CONVERSION ZONE WITH A CATALYST UNDER SUITABLE CONDITIONS TO EFFECT CONVERSION INTO DESIRED COMPOUNDS, REMOVING AN EFFLUENT COMPRISING NORMALLY GASEOUS AND NORMALLY LIQUID PRODUCTS OF CONVERSION FROM SAID CONVERSION ZONE, DIVERTING A PORTION OF SAID EFFLUENT TO A PRODUCT RECOVERY SYSTEM, DIVIDING ANOTHER PORTION OF SAID EFFLUENT INTO TWO STREAMS, COOLING ONE OF SAID STREAMS TO REMOVE NORMALLY LIQUID CONSTITUENTS, COMBINING COOLED UNCONDENSED GAS FROM SAID COOLING TREATMENT WITH HOT GASES CONTAINING HIGHER BOILING COMPONENTS OF THE OTHER OF SAID STREAMS SO AS TO EFFECT CONDENSATION OF HIGHER BOILING COMPONENTS OF SAID OTHER STREAM IN THE FORM OF A FOG, RECYCLING SAID COMBINED STREAM RETAINING FOR THEREIN TO SAID CONVERSION ZONE TO SUPPLY SAID COOLANT, AND RETAINING A RECYCLE RATIO OF RECYCLE GAS TO FRESH FEED BETWEEN 0.5 TO 1 AND 4 TO
 1. 